In petroleum reservoirs, permeability affects the overall production capability of a wellbore. Permeability can vary greatly based upon several factors, including the overall type of material that the wellbore penetrates. Permeability can also change in a wellbore as the wellbore progresses through increasing lengths. Vertical permeability anisotropy refers to the change of permeability as the wellbore penetrates layer upon layer in the geological stratum.
Permeability, however, may also change in the horizontal plane. Horizontal permeability anisotropy can be just as important, if not more important, to the petroleum well. Such horizontal plane anisotropy can affect the overall well output if the horizontal permeability components vary a great deal or if the anisotropy is located in specific areas of the geological stratum. Identification of such horizontal anisotropy, however, is difficult. There are currently no standardized tests to determine horizontal permeability anisotropy for geological stratum. In addition to the above, single-packer configurations or probe configurations have not been utilized to determine such horizontal permeability anisotropy.
Finding a statistically meaningful method to determine horizontal permeability anisotropy can provide large benefits for operators of well drilling equipment. If extreme variation of horizontal permeability components is found, such seemingly profitable payzones in formations may be discarded in favor of more productive formation features.
Such investigations can minimize needless drilling in remote areas, for example, if the need for such drilling would not provide dividends in light of the expanded costs of drilling. Investigations performed in high value wells, such as deep water ocean drilling, where costs can range in the millions of dollars per day, can have a significant impact on the overall return of drilling. In addition to the above, there is a need to be able to identify horizontal permeability anisotropy with downhole equipment, away from expensive laboratory tests used in conventional applications. Such field capable identification would be of significant benefit as no conventional applications exist that would quickly and reliably identify horizontal permeability anisotropic conditions in modem wellbores and well drilling.